Testes? Mas isso não aumenta o tempo de projecto? Não quero... Pedro Rosa http://netpont o.org 1ª Reunião em Coimbra - 09/04/2011
May 13, 2015
Testes? Mas isso não aumenta o tempo de projecto? Não quero...
Pedro Rosa
http://netponto.org1ª Reunião em Coimbra - 09/04/2011
Patrocinadores desta reunião
Pedro Rosa
LinkedInhttp://pt.linkedin.com/in/pedrobarraurosa
Twitterhttp://twitter.com/pedrorosa
Agenda
1. Why?2. Code Coverage3. Static / Dynamic Analysis4. Unit Testing5. WebTesting6. Load (Performance) Testing
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1996 1998 2000 2002 2004 20060%
50%
100%
150%
Percent OverrunFailed Succedded Challenged
Source: Standish Group, 2006 Third Quarter Research Report, CHAOS Research Results
The State of Application Development
• Only 1 in 3 projects succeed • Projects cost 50% more then budgeted• Lack of software quality cost US businesses $59B / year.• Bugs account for 55% of downtime
on average professional coders make 100 to 150 errors in every 1000 lines of code they write
software bugs cost the US economy an estimated $59.5 billion every year
last year, canceled projects cost firms $67 billion; overruns on the other projects racked up another $21billion
Need something a little more concrete?
USS Yorktown, SmartShip
• crew member entered 0 in a data entry field, caused a “divide by 0” error that shut down propulsion
• dead in the water for 2hrs 45mins
Ariane 5 Flight 501• re-used code from ariane 4, but
took a different flight path because of different booster design
• conversation from 64bit float to 16bit signed int caused overflow (exception handler was disabled for perf reasons)
• cost: > $370 million @ 1996 prices
F-22 Raptor• deploying overseas to japan the
first time
• crossed international dateline, computers crashed losing all navigation and communications systems
• clear weather allowed them to follow tankers back to hawaii
Raptor is likely the most advanced manned aircraft that will ever fly…
Need something a little more visual?
Still Not Convinced?
Training
Conditioning
Climbing
Training Phase
Cost of Failure
Development
Test
Release
Software Phase
Cost of Bugs
Push Quality Upstream
Development
Test
Release
Software Phase
Cost of Bugs
Generalist SpecialistManual Testing Some scripting
Creates scripts to set up lab, create data
Strong scripting skills
Some coding skills
Strong coding
Develops fully automated testing procedures
Expert coding skills
Where does testing happen?
Black Box Testing
White Box Testing
API Testing
70% of testing happens here
Majority of test tools target here
Visual Studio 2010
Test Manager 2010
Manual Testing
Layer Diagram
UML Modeling
Load Testing Web Testing
Test Case ManagementIntelliTrace™
Architecture Explorer Fast Forward for Manual Testing
Logical Class Designer
Cloud Development
Office Development
Windows Development
New WPF Editor Customizable IDE
Multi-core DevelopmentSilverlight Tools
Web Development
SharePoint Development
Generate from Usage
Static Code Analysis
Database Deployment
Code Metrics
Database Unit Testing Test Data Generation
Test Impact AnalysisUI Test Automation
Code Coverage
Performance Profiling
Database Change Mgmt
Visual Studio 2010 Test Types Unit Test Database Unit Test Web Performance Test Load Test Manual Test (Test Case) Generic Test Ordered Test Coded UI Test
What is Unit Testing?
Unit Test – Definition
“Program testing can be used to show the presence of bugs, but never to show their absence!”
Edsger Dijkstra, [1972]
A unit test is a piece of code written by a developer that exercises a very small, specific area of functionality of the code being tested.
Manual Testing You have already done unit testing
Manually, by hand
Manual tests are less efficient Not structured Not repeatable Not on all your code Not easy to do as it should be
Unit Test Exampleint Sum(int[] array){ sum = 0; for (int i=0; i<array.Length; i++) sum += array[i]; return sum;}
void TestSum(){ if (Sum(new int[]{1,2}) != 3) throw new TestFailedException("1+2 != 3"); if (Sum(new int[]{-2}) != -2) throw new TestFailedException("-2 != -2"); if (Sum(new int[]{}) != 0) throw new TestFailedException("0 != 0");}
Unit Testing Some Facts• Tests are specific pieces of code• Unit testing framework is needed– Visual Studio Team Test– NUnit– MbUnit
• Unit tests are written by developers, not by QA engineers
• Unit tests are released into the code repository along with the code they test
Unit Testing – More Facts• All classes should be tested– Test anything that could have bugs
• All methods should be tested– Trivial code may be omitted – E.g. property getters and setters
• Ideally all unit tests should pass before check-in into the source control repository
Why Unit Tests?Why Unit Tests?• Unit tests dramatically decrease the number of
defects in the code • Unit tests improve design • Unit tests are good documentation• Unit tests reduce the cost of change• Unit tests allow refactoring• Unit tests decrease the defect-injection rate due to
refactoring / changes
Code and Test vs. Test Driven Development
Unit Testing ApproachesUnit Testing Approaches
• "Code and Test" approach• Classical approach
• "Test First" approach• Test driven development (TDD)
Write code
Write unit test
Run and succeed
Code and Test ApproachCode and Test Approach
Time flow
Pick а test
Compile and fail
Write code to pass test
Write enough code to compile
Run test and fail
Create a test list
Test Driven DevelopmentTest Driven Development
Time flow
Write test
Remove duplication
Why Test Driven Development?
• Helps find design issues early and avoids rework
• Writing code to satisfy a test is a focused activity – less chance of error
• Tests will be a more comprehensive than when written after code
Unit Testing Frameworks and Visual Studio Team Test
Unit Testing Frameworks
• JUnit– The first popular unit testing framework– Based on Java
• Similar frameworks have been developed for a broad range of computer languages– NUnit – for C# and all .NET languages– cppUnit, jsUnit, PhpUnit, PerlUnit, ...
• Visual Studio Team Test (VSTT)– Developed by Microsoft, integrated in VS
Visual Studio Team Test – Features• Team Test (TT) is very well integrated with
Visual Studio–Create test projects and unit tests– Execute unit tests–View execution results–View code coverage
• Located in the assembly Microsoft.VisualStudio.QualityTools.UnitTestFramework.dll
Visual Studio Team Test – Attributes• Test code is annotated using custom attributes
[TestClass] – denotes a class holding unit tests [TestMethod] – denotes a unit test method [ExpectedException] – test causes an exception [Timeout] – sets a timeout for test execution [Ignore] – temporary ignored test case [ClassInitialize], [ClassCleanup] – setup /
cleanup logic for the testing class [TestInitialize], [TestCleanup] – setup /
cleanup logic for each test case
Assertions
• Predicate is a true / false statement • Assertion is a predicate placed in the program
code – Indicates that the developer thinks that the predicate is
always true at that place– If an assertion fails, the method call does not return
and an error is reported– Example:Assert.AreEqual(expectedValue, actualValue, "Error message.");
VSTT – Assertions• Assertions check condition and throw exception if condition is not satisfied• Comparing values
– AreEqual(expected value, calculated value [,message]) – compare two values for equality
• Comparing objects
– AreSame(expected object, current object [,message]) – compare object references
VSTT – Assertions (2)• Checking for null value– IsNull(object [,message])– IsNotNull(object [,message])
• Conditions– IsTrue(condition)
– IsFalse(condition)
• Forced test fail– Fail(message)
The 3A Pattern• Arrange all necessary preconditions and inputs• Act on the object or method under test• Assert that the expected results have occurred[TestMethod]public void TestDeposit(){ BanckAccount account = new BanckAccount(); account.Deposit(125.0); account.Deposit(25.0); Assert.AreEqual(150.0, account.Balance, "Balance is wrong.");}
VSTT – Examplepublic class Account{ private decimal balance; public void Deposit(decimal amount) { this.balance += amount; } public void Withdraw(decimal amount) { this.balance -= amount; } public void TransferFunds( Account destination, decimal amount) { ... } public decimal Balance { ... }}
VSTT – Example (2)using Microsoft.VisualStudio.TestTools.UnitTesting;
[TestClass]public class AccountTest{ [TestMethod] public void TransferFunds() { Account source = new Account(); source.Deposit(200.00M); Account dest = new Account(); dest.Deposit(150.00F); source.TransferFunds(dest, 100.00F); Assert.AreEqual(250.00F, dest.Balance); Assert.AreEqual(100.00F, source.Balance); }}
VSTT – Screenshot
Visual Studio Team Test
Live Demo
Unit Testing Best Practices
Naming Standards for Unit Tests
• The test name should express a specific requirement that is tested–Usually prefixed with [Test]– E.g. TestAccountDepositNegativeSum()
• The test name should include– Expected input or state – Expected result output or state–Name of the tested method or class
Naming Standards for Unit Tests Example
• Given the method:
with requirement to ignore numbers greater than 100 in the summing process
• The test name should be:
Sum_NumberIgnoredIfGreaterThan100
public int Sum(params int[] values)
When Should a Test be Changed or Removed?
• Generally, a passing test should never be removed– These tests make sure that code changes don’t break
working code• A passing test should only be changed to make it
more readable• When failing tests don’t pass, it usually means there
are conflicting requirements
When Should a Test be Changed or Removed? (2)
• Example:
• New features allows negative numbers
[ExpectedException(typeof(Exception), "Negatives not allowed")]void Sum_FirstNegativeNumberThrowsException(){ Sum (-1,1,2);}
When Should a Test be Changed or Removed?(3)
• New developer writes the following test:
• Earlier test fails due to a requirement change
void Sum_FirstNegativeNumberCalculatesCorrectly(){ int sumResult = sum(-1, 1, 2); Assert.AreEqual(2, sumResult);}
When Should a Test be Changed or Removed? (4)
• Two course of actions:1. Delete the failing test after verifying if it’s valid2. Change the old test:
• Either testing the new requirement• Or test the older requirement under new settings
Tests Should Reflect Required Reality
• What’s wrong with the following test?
• A failing test should prove that there is something wrong with the production code– Not with the unit test code
int Sum(int a, int b) –> returns sum of a and b
public void Sum_AddsOneAndTwo(){ int result = Sum(1,2); Assert.AreEqual(4, result, "Bad sum");}
What Should Assert Messages Say?
• Assert message in a test is one of the most important things– Tells us what we expected to happen but didn’t, and what
happened instead– Good assert message helps us track bugs and understand
unit tests more easily• Example:– "Withdrawal failed: accounts are not supposed to have
negative balance."
What Should Assert Messages Say? (2)
• Express what should have happened and what did not happen– “Verify() did not throw any exception”– “Connect() did not open the connection before
returning it”• Do not:– Provide empty or meaningless messages – Provide messages that repeat the name of the test case
Avoid Multiple Asserts in a Single Unit Test
• Avoid multiple asserts in a single test case– If the first assert fails, the test execution stops for this test
case– Affect future coders to add assertions to test rather than
introducing a new one
void Sum_AnyParamBiggerThan1000IsNotSummed() { Assert.AreEqual(3, Sum(1001, 1, 2); Assert.AreEqual(3, Sum(1, 1001, 2); Assert.AreEqual(3, Sum(1, 2, 1001);}
Unit Testing – The Challenge
• The concept of Unit Testing has been around for many years
• New methodologies in particular XP, have turned unit testing into a cardinal foundation of software development
• Writing good & effective Unit Tests is hard!– This is where supporting integrated tools and suggested
guidelines enter the picture• The ultimate goal is tools that generate unit tests
automatically
What is a load test?
• An automated collection of tests run in parallel to simulate multiple users or systems• Load tests run software unit tests, database unit tests,
and web performance tests• Visual Studio captures details metrics while the load test
runs
Load Test ConceptsScenario• A collection of load test parameters that
simulate real world scenario.Load Pattern• Determines the number of users the scenario
simulates. May be constant or stepped to simulate an increasing number of users
Test Mix• Determines the unit tests and web tests.Network Mix• Determines the connection speeds used by
virtual usersRun Settings• A set of properties that determine the way the
load test runs
Core Scenarios
• Single user performance testing• Create and debug Web
Performance Tests• Use Coded UI tests to measure
end user performance• Run performance tests• Analyze results• Report to stakeholders• Fix the problems using the
profiler
Network Emulation
• Productizing NEWT network device driver• Throttles bandwidth, introduces latency and errors
at the network layer• Scenarios• Single user testing over slow network• Automated performance testing over slow links
Web Performance Test Recorder
Visual Studio
Recorder Listener
Internet Explorer
Browser Control
Wininet Shim
Wininet
Browser Recorder
Wininet Recorder
Browser events
Intercepts wininet calls
Merging Recorder
Record events
Record eventsRecord events
Recorder BHO
Visual Studio Launches Internet Explorer
Web Test Recorder Plugin
Visual Studio
Recorder Listener
Record events
Internet Explorer
Browser Control
Wininet Shim
Wininet
Browser Recorder
Wininet Recorder
Browser events
Intercept s wininet calls
Merging Recorder
Record events
Record events
Recorder BHO
Visual Studio Launches Internet Explorer
WebTest RecorderPlugins
Recorder Result
Recorded Web Test
Load Test Agent ArchitectureVisual Studio Ultimate 2010
Test Controller
Test Controller manages test agents
Test agents run tests and collect data
Test agent #1
CollectorAgent
Asp.NetProfiler
Target Server
Test agent #2
Test AgentRun Tests
Test agent #3
Visual Studio Team Test
Live Demo
Questions?
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?? ?
Patrocinadores desta reunião
Próximas reuniões presenciais
• 09/04/2011 - Abril (Coimbra)• 16/04/2011 - Abril (Lisboa)• 21/05/2011 - Maio (Lisboa)• 18/06/2011 - Junho (Lisboa)
Reserva estes dias na agenda! :)
Obrigado!
Pedro Rosahttp://pt.linkedin.com/in/pedrobarraurosahttp://twitter.com/pedrorosa